Corkscrew shape for right-sided cardiac device

ABSTRACT

A catheter includes a catheter body, a pump assembly and a cannula. The pump assembly can be disposed at a distal end of the catheter body and has a distal portion. The cannula can be coupled to the distal end portion of the pump assembly and can include a proximal cannula portion and a distal cannula portion. The distal cannula portion has an approximately helical shape which can allow the cannula to be inserted into a patient&#39;s right heart and pump blood therethrough. In certain implementations, the distal tip of the helical shape has a slight bias relative to the main helix to further facilitate delivery of the device. In certain applications this bias is toward the central axis of the helix.

BACKGROUND

A ventricular assist device (VAD), such as a percutaneous intracardiacheart pump assembly, can be introduced in the heart to deliver bloodfrom the heart into an artery. VADs are designed to assist either theright or left ventricle or both at once. When deployed in the heart, aVAD can pull blood from one chamber of the heart and expel it into theaorta or pulmonary artery to facilitate the flow of blood through theheart and throughout the body. In one common approach, VADs are insertedby a catheterization procedure through the femoral artery into the leftheart of a patient, or through the femoral vein into the right heart ofthe patient.

VADs designed for right heart assistance (RVADs) can extend through thepulmonary valve and into the pulmonary artery in order to expel bloodinto the pulmonary artery. To properly position certain RVADs, thedevices must be passed through the inferior vena cava, right atrium,tricuspid valve, right ventricle and finally the pulmonary valve. Thestiffness of these RVADs typically must be higher than the stiffness ofother cardiac devices (e.g., Swan-Ganz catheters) which are typicallysmaller and are not designed to prevent displacement due to the force offluid flow. While the higher stiffness of the RVAD enables long-term useof the device, it may also increase the difficulty of inserting theRVAD. This difficulty is exacerbated in the case of patients withabnormal right heart anatomies because RVADs may be designed based on amean patient population. In these cases, the relatively stiff cannula ofthe RVAD can interfere with positioning the device in the pulmonaryartery after the device passes through the tricuspid valve. Accordingly,some medical practitioners may experience difficulties in placing theRVAD in certain patients, particularly at the stage of advancing theRVAD through the tricuspid valve toward the pulmonary artery.

SUMMARY

Systems, methods, and devices for a VAD shaped to improve delivery ofthe VAD into the right heart are presented herein. The VAD includes acannula having an approximately helical shape. The helical shapefacilitates the advancement of the cannula into and/or through the rightventricle. In particular, the shape may facilitate advancement throughthe tricuspid and/or pulmonary valves. The shape of the cannulafacilitates or enables the advancing of the device into the heart usinga twisting, rotating, or screw motion. Such a motion can allow thecannula to more easily proceed through the patient's anatomy andparticularly through the tricuspid valve and toward the pulmonaryartery. The distal tip of the helical cannula can also be shaped tofacilitate this motion. The tip may be angled toward the axis of thecannula's helical shape and may thus have a tighter curvature than theremainder of the cannula, such that the distal tip is oriented in afavorable direction during device delivery. The shape of the cannula canmimic the internal anatomy of the pathway that the device takes throughthe heart so that correct positioning of the device is achieved in themajority of patients without difficulty.

The helical shape of the cannula can be determined from analysis ofmedical images of patient right heart anatomies. The average right heartanatomy of the areas in which the cannula is to be positioned andthrough which the cannula passes may possess a somewhat helical shape.Therefore, pairing a cannula's helical shape with the shape of the rightheart anatomy can allow the cannula to move through the heart anatomymore easily than a cannula lacking a helical shape matching the anatomy.In some implementations, the VAD, when positioned in the right heart,has an outflow port positioned distal to the pulmonary valve and aninflow port located in the inferior vena cava. The cannula of the VADcan traverse the inferior vena cava, right atrium, tricuspid valve,right ventricle, and pulmonary valve.

In one aspect, a catheter comprises a catheter body, a pump assembly,and a cannula. The catheter body has a distal end, a proximal end, and alongitudinal axis. The pump assembly is disposed at the distal end ofthe catheter body and has a distal portion. The cannula is coupled tothe distal end portion of the pump assembly. The cannula comprises aproximal cannula portion and a distal cannula portion. The distalcannula portion has an approximately helical shape. In certainimplementations, the helical shape approximated by the distal cannulaportion has an axis parallel to the longitudinal axis of the catheterbody. In some implementations, the distal tip of the cannula is angledtoward a center of the helical shape axis.

In some implementations, the helical shape approximated by the distalcannula portion has a radius between about 10 mm and 50 mm. In certainimplementations, the helical shape approximated by the distal cannulaportion has a radius between about 20 mm and 40 mm. In someimplementations, the helical shape approximated by the distal cannulaportion has a radius of about 30 mm. In certain implementations, thehelical shape approximated by the distal cannula portion has a pitchbetween about 50 mm and 140 mm. In some implementations, the helicalshape approximated by the distal cannula portion has a pitch betweenabout 70 mm and 120 mm. In certain implementations, the helical shapeapproximated by the distal cannula portion has a pitch of about 90 mm.In some implementations, the helix completes one turn. In someimplementations, the length of the distal cannula portion is abouttwo-thirds of a total length of the cannula. In certain implementations,the total length of the cannula is about 17 cm.

In certain implementations, the cannula is configured to extend throughthe tricuspid valve and the pulmonary valve into the inferior vena cavawhen positioned in the right heart. In some implementations, the cannulais configured to be approximately perpendicular to a plane defined bythe tricuspid valve during entry through the right atrium into the rightventricle. In certain implementations, the curvature of the distal endof the cannula is configured such that a distal tip of the cannulapoints toward the pulmonary valve after passing through the tricuspidvalve.

In some implementations, the helical shape of the cannula is configuredto match an average patient anatomy of the right atrium, tricuspidvalve, right ventricle, pulmonary valve, and pulmonary artery duringplacement in the right heart. In certain implementations, the cannula issized for percutaneous delivery. In some implementations, the cannulahas a diameter of about 22 Fr. In certain implementations, the catheterfurther includes a flexible extension coupled to the distal cannulaportion.

In another aspect, a heart pump assembly comprises a rotor, a housing,and a cannula. The housing is sized for percutaneous insertion andencloses the rotor. The housing has a distal end portion coupled to thecannula. The cannula comprises a proximal cannula portion and a distalcannula portion. The distal cannula portion has an approximately helicalshape. In some implementations, the helical shape approximated by thedistal cannula portion has an axis parallel to a longitudinal axis ofthe proximal cannula portion. In certain implementations, the helicalshape approximated by the distal cannula portion has a diameter betweenabout 20 mm and 40 mm. In some implementations, the helical shapeapproximated by the distal cannula portion has a pitch between about 70mm and 120 mm. In certain implementations, a distal tip of the cannulais angled toward a center of the helical shape axis to ensure properorientation while passing through the anatomy.

In another aspect, a method for placing a catheter in a patient's rightheart includes advancing the catheter through a femoral vein to theinferior vena cava, simultaneously rotating and translating thehelically-shaped distal tip through the tricuspid valve and into theright atrium in a screw-like motion, and advancing the helically-shapeddistal tip through the pulmonary valve into the pulmonary artery. Thecatheter comprises a heart pump and a helically-shaped distal tip. Insome implementations, the method further includes positioning thecatheter across the pulmonary valve such that an outlet port ispositioned in the pulmonary artery. In certain implementations, themethod further includes positioning the catheter such that an inlet portis positioned in the inferior vena cava. In some implementations,advancing the catheter through the femoral vein comprises advancing thecatheter over a guidewire.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 shows a front view of a catheter including a cannula having ahelical shape;

FIG. 2A and FIG. 2B show a detailed view of a catheter including acannula having a helical shape for right heart insertion;

FIG. 3 shows an illustrative view of multiple overlays of the cannula atvarious positions during insertion into the right heart;

FIG. 4 shows a top view of a cannula having a helical shapecharacterized by a diameter;

FIG. 5 shows a front view of a cannula having a helical shapecharacterized by a diameter;

FIG. 6 shows a front view of a cannula having a helical shapecharacterized by a pitch;

FIG. 7 shows a side view of a cannula having a helical shapecharacterized by a pitch;

FIG. 8 shows a catheter including a cannula having a helical shapepositioned in the right heart of a patient; and

FIG. 9 shows an illustrative process for placing a cannula in apatient's right heart.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, method, and devicesdescribed herein, certain illustrative embodiments will be described.Implantable cannulas according to the embodiments and features describedherein can be implanted with or without use of a guidewire. Although theembodiments and features described herein describe a cannula with ahelical shape matched to an average heart anatomy of a percentage of apatient population, the cannula may be produced so as to fit a helixdescribing the anatomical structure of a single patient, in particularif the patient's heart anatomy differs from the average anatomy of thematched patient population, or if the patient is a child.

Systems, methods, and devices for a VAD shaped to improve delivery ofthe VAD into the right heart are presented herein. The VAD includes acannula having an approximately helical shape. The helical shapefacilitates the advancement of the cannula into and/or through the rightventricle. In particular, the shape may facilitate advancement throughthe tricuspid and/or pulmonary valves. The shape of the cannulafacilitates or enables the advancing of the device into the heart usinga twisting, rotating, or screw motion. Such a motion can allow thecannula to more easily proceed through the patient's anatomy andparticularly through the pulmonary valve into the pulmonary artery. Thedistal tip of the helical cannula can also be shaped to facilitate thismotion. The tip may be angled toward the axis of the cannula's helicalshape and may thus have a tighter curvature than the remainder of thecannula. The shape of the cannula can mimic the internal anatomy of thepathway that the device takes through the heart so that correctpositioning of the device is achieved in the majority of patientswithout difficulty.

The helical shape of the cannula was determined from analysis of medicalimages of patient right heart anatomies. The average right heart anatomyof the areas in which the cannula is to be positioned and through whichthe cannula passes may possess a somewhat helical shape. Therefore,pairing a cannula's helical shape with the shape of the right heartanatomy can allow the cannula to move through the heart anatomy moreeasily than a cannula lacking a helical shape matching the anatomy. Insome implementations, the VAD, when positioned in the right heart, hasan outflow port positioned distal to the pulmonary valve and an inflowport located in the inferior vena cava at the level of the diaphragm.The cannula of the VAD can traverse the inferior vena cava, rightatrium, tricuspid valve, right ventricle, and pulmonary valve.

FIG. 1 shows a front view of a catheter 100 including a cannula 112having a helical shape according to certain implementations. Thecatheter 100 includes a catheter body 103, a pump assembly 108, and acannula 112 having a pre-formed helical shape. The catheter body 103 hasa distal end 102, a proximal end 104, and a longitudinal axis 106. Thepump assembly 108 is coupled to the distal end 102 of the catheter body103. The cannula 112 is coupled to a distal end portion 110 of the pumpassembly 108. The cannula 112 has a proximal cannula portion 114 and adistal cannula portion 116. The distal cannula portion 116 has anapproximately helical shape. The approximately helical shape has acentral axis 107 which is substantially parallel to the longitudinalaxis 106. The proximal cannula portion 114 may b e approximatelyparallel to the longitudinal axis 106 of the catheter body 103 and maybe approximately straight.

The helically-shaped distal cannula portion 116 includes a partialrotation about the central axis 107. The helical shape of the distalcannula portion 116 may approximate the anatomy of the right heart,allowing the catheter 100 to be inserted into the right heart of apatient with a screw-like motion. A distal tip 126 of the distal cannulaportion 116 may deviate from the helical shape in order to furtherapproximate the right heart anatomy. For example, the distal tip 126 maybe angled toward the central axis 107 i.e., having a greater curvaturerelative to the remainder of the distal cannula portion 116. In certainimplementations, the distal tip 126 may have less of a curvaturerelative to the remainder of the distal cannula portion 116. In certainimplementations, the distal tip 126 of the cannula 112 may narrow towardthe distal tip 126 of the distal cannula portion 116, which can furtherfacilitate passage through the heart valves. In certain implementations,a flexible extension can be connected to the distal tip 126 to preventtraumatic contact of the distal tip 126 with interior walls of the heartfollowing insertion.

The catheter 100 can be advanced into the right heart in the followingmanner. First, the distal tip 126 of the cannula 112 is advanced throughthe inferior vena cava into the pulmonary artery. Next, the catheter 100may be rotated (e.g., clockwise) and advanced in a screw motion throughthe tricuspid valve toward the pulmonary artery. Then, the screw motionmay be repeated to advance the distal tip 126 through the pulmonaryvalve into the pulmonary artery. When the distal tip 126 of the cannula112 is positioned within the pulmonary artery, the pump assembly 108 mayremain in the inferior vena cava. The pump 108 may be activated oncethis position is achieved to pump blood from the inferior vena cava intothe pulmonary artery. Thus, by enabling the advancing of the cannula 112by a screw motion, the shape of the distal cannula portion 116facilitates correct positioning of the catheter 100 in the right heart.

FIG. 2A and FIG. 2B show a detailed view of a catheter 200 having acannula with a helical shape for insertion into the right heartaccording to certain implementations. The catheter 200 includes acatheter body 203, a pump assembly 208, and a cannula 212. The catheterbody 203 includes a proximal end 204 and a distal end 202. The distalend 202 of the catheter body 203 is coupled to the pump assembly 208.The cannula 212 is coupled to a distal end portion 210 of the pumpassembly 208. The cannula 212 includes a substantially straight proximalcannula portion 214, a substantially helical distal cannula portion 216,a distal tip 226, a distal end 218, inlet ports 222, outlet ports 220,and a flexible projection 224.

The cannula 212 is sized to be positioned such that the cannula 212traverses the inferior vena cava, right atrium, tricuspid valve, rightventricle and pulmonary valve of the heart. This allows the inlet ports222 to be positioned in the inferior vena cava when the outlet ports 220are positioned in the pulmonary artery. In some implementations, thelength 229 of the cannula 212 is 17 cm. In certain implementations, thelength 229 of the cannula is 10 cm, 12, cm, 15 cm, 17 cm, 18 cm, 20 cmor any other suitable length. The cannula 212 is constructed to allowfluid to flow into the inlet ports 222, through the cannula 212, and outthe outlet ports 220. The fluid may be propelled through the cannula 212by a rotor located in the pump assembly 208. The cannula 212 may beconfigured to be relatively stiff in order to increase the stability ofthe cannula 212 once in place in the right heart. The curvature of thecannula 212 may reduce the need for flexibility of the cannula 212during insertion.

The cannula 212 is also sized for passage through a femoral artery andother vasculature of a patient. In some implementations, the cannula 212has a cannula diameter 228 of about 22 Fr. In certain implementations,the cannula 212 has a cannula diameter 228 of 7 Fr, 8 Fr, 10 Fr, 11 Fr,12 Fr, 18 Fr, 20 Fr, 24 Fr, or any other suitable diameter. The cannuladiameter 228 may be approximately constant along the length 229 of thecannula 212.

The distal portion 216 of the cannula 212 helps the cannula 212 to bepositioned within the right heart of a patient. The helical shape of thedistal cannula portion 216 allows the cannula 212 to be dynamicallypositioned in the right heart using a screw-like rotation motion thatfollows the anatomy of the right heart. The distal cannula portion 216may have a curvature that mimics the anatomical pathway of the cannula212 during positioning in the right heart. In some implementations, thedistal cannula portion 216 has a length of about two-thirds of the totallength 229 of the cannula 212.

The distal tip 226 of the cannula 212 further facilitates insertion ofthe cannula 212. The distal tip 226 may deviate from the helixapproximating the shape of the remainder of the distal cannula portion216. In particular, the distal tip 226 of the cannula 212 may haveeither a greater or lesser curvature than the remainder of the distalcannula portion 216. The curvature of the distal tip 226 causes thedistal tip 226 to be oriented toward the tricuspid valve during initialinsertion of the cannula 212 into the right atrium. This facilitatesinsertion because, once in the right atrium, the cannula 212 must make arelatively tight turn toward the tricuspid valve to enter the rightventricle. The shape of the distal tip 226 also causes the distal tip226 to be oriented toward the pulmonary valve upon entry into the rightventricle. This facilitates insertion because, once in the rightventricle, the cannula 212 must be oriented toward the pulmonary valveto enter the pulmonary artery. In some implementations, the distal tip226 of the cannula 212 narrows toward the distal end 218 of the distalcannula portion 216, which can further facilitate passage through theheart valves.

Additionally, the flexible extension 224 is connected to the distal end218 of the distal tip 226 to help prevent traumatic contact with theinterior walls of the heart after insertion of the cannula 212 into theheart. The flexible projection 224 may be formed as a pigtail, a ball, aflexible rod, or as any other suitable extension from the distal end ofthe cannula portion 218. In some implementations, the flexibleprojection 224 mechanically, but not hydraulically, extends the cannula212. The flexible projection 224 may prevent the cannula 212 fromtraumatically engaging with heart tissue. In certain implementations,the distal tip 226 does not include the flexible projection 224.

The pump assembly 208 may contain a rotor (not shown) which may bedriven by an implantable or external drive unit. The pump assembly 208comprises a housing 213 which may be comprised of a different materialthan the cannula 212 or catheter 203. The rotor of the pump assembly 208may be located in the housing 213 and attached to a drive shaft.Although an embodiment with an implantable motor is shown in FIG. 2A, insome implementations the unit driving the drive shaft is locatedexternal to the patient's body and the drive shaft extends through thecatheter body 203. In some implementations, a motor driving the driveshaft is enclosed within the pump assembly 208. Any suitable pump and/ordrive known in the art may be used.

The pump assembly 208 is configured to provide a fluid flow into thecannula 212 at the inlet ports 222, through the cannula 212, and out theoutlet ports 220. The pump assembly 208 may be configured to provide aflow rate of 4 liters per minute (lpm 0 or more within the right heartof a patient. In some implementations, the pump assembly 208 provides aflow rate of 3 lpm, 3.5 lpm, 4 lpm, 4.5 lpm 5 lpm, 6 lpm or any othersuitable flow rate. In some implementations, the flow rate is chosenbased on the needs of the patient.

FIG. 3 shows a cannula 312 in four successive positions 312 a-312 dduring insertion into the heart 301 according to certainimplementations. The heart includes an inferior vena cava 336, a rightatrium 338, a tricuspid valve 340, a right ventricle 342, a pulmonaryvalve 344, and a pulmonary artery 346. The cannula 312 includes a distalcannula portion 316, and a distal tip 326. The cannula 312 follows anapproximately helical trajectory 345 from position 312 a to 312 d as itis inserted into the heart 301. The distal tip 326 leads the cannula 312along the helical trajectory 345.

The first position 312 a shows the cannula after it has been introducedthrough the inferior vena cava 336 into the right atrium 338 of thepatient. The distal tip 326 a of the cannula 312 a is oriented such thatthe distal tip 326 a is pointed toward the tricuspid valve 340. Thedistal tip 326 of the cannula 312 deviates slightly from the helicaltrajectory 345 because the distal tip 326 is angled toward a centralaxis of the helical shape formed by the distal cannula portion 316. Insome implementations, the cannula 312 is inserted into the right heart301 over a guidewire. In certain implementations, a flexible projectionis attached to the distal end of the cannula 312 which preventstraumatic contact of the cannula 312 with the interior walls of theheart 301 by providing a flexible extension of the cannula 312. In someimplementations, a flexible extension is straight during insertion andis curved upon removal of a guidewire after insertion.

The second position 312 b shows the cannula 312 after it has beenadvanced in a screw motion through the tricuspid valve 340 into theright ventricle 342. The cannula 312 in position 312 b is approximatelyperpendicular to a plane defined by the tricuspid valve 340 and ispositioned to advance the cannula 312 from the inferior vena cava 336through the tricuspid valve 340 and then from the right ventricle 342through the pulmonary valve 344 to the pulmonary artery 346.

The third position 312 c shows the cannula 312 just before passagethrough the pulmonary valve 344. The catheter advances from the secondposition 312 b to the third position 312 c in a screw-like motion alongthe helical trajectory 345. This motion advantageously orients thedistal tip 326 c towards the pulmonary valve 344.

The fourth position 312 d shows the cannula 312 after the cannula hasbeen advanced through the pulmonary valve 344 into the pulmonary artery346. The catheter advances from the third position 312 c to the fourthposition 312 d in a screw-like motion along the helical trajectory 345.Once the cannula 312 is positioned in the fourth position 312 d, pumpoperation may be initiated to pump blood from the inferior vena cava 336to the pulmonary artery 346.

As shown by the illustrative positions 312 a-d, the helical shape of thecannula 312 allows a screw motion to be used to rotate and translate thecannula 312 through the right heart of a patient. In someimplementations, the cannula 312 is advanced into position over aguidewire or through a sheath. The cannula 312 may be configured forshort-term use, such as during an emergency procedure or in conjunctionwith an imaging procedure. In some implementations, the cannula 312 maybe configured for long-term use as a fully implantable heart pump. Thecannula 312 may be used for long-term implantation in a patient(e.g., >1 hr, >3 hr, >6 hr, >12 hr, >24 hr, >2 days, >10 days, >20days, >45 days, >60 days or any suitable duration). The cannula 312 maybe inserted into the patient's vasculature surgically or percutaneously.

FIG. 4 shows a top view of a cannula 412 according to certainimplementations having a helical shape characterized by a diameter 432,and FIG. 5 shows a front view of the cannula 412. The curve of thecannula 412 may be approximated by helices 432 a-c of varying diameters.The cannula 412 is approximated by a helix 432 b with a diameter ofabout 30 mm. In some implementations, the helix 432 has a diameter ofabout 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, or any other suitable diameter.The diameter of helix 432 b may approximate an average right heartanatomy of a patient population. Toward its proximal portion, thecannula 412 is more closely approximated by the helix 432 c which has arelatively large diameter (e.g., 40 mm). Toward its distal tip 426, thecannula 412 is more closely approximated by the helix 432 a which has arelatively small diameter (e.g., 20 mm). In some implementations, thecannula 412 may be approximately described by a uniform helix. In someimplementations, the distal tip 426 of the cannula 412 may be orientedin a different direction than the main helix 407 to facilitate passagethrough the anatomy. In some implementations, the distal tip 426 of thecannula 412 may deviate from the helix by angling toward a center axisof the helix 407. In some implementations, the helical shapeapproximated by the cannula 412 may include a full turn. In someimplementations, the helical shape approximated by the cannula 412 mayinclude less than one full turn. In some implementations, the helicalshape approximated by the cannula 412 may complete a turn of 180°, 200°,220°, 240°, 260°, 280°, 300°, 330°, 360° or any other suitable turn.

FIG. 6 shows a front view of a cannula 612 according to certainimplementations having a helical shape characterized by a pitch 634, andFIG. 7 shows a side view of the cannula 612. The curve of the cannula612 may be approximated by helices 634 a-c of varying pitches. In apreferred implementation, the shape of the cannula 612 is approximatedby a helix 634 b with a pitch of about 90 mm. In some implementations,the helix 634 has a pitch of about 50 mm, 60 mm, 70 mm, 80 mm, 90 mm,100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, or any other suitablepitch. The cannula 612 may be approximated by a helix 634 b with arelatively low pitch (e.g., 70 mm) at a proximal end of the distalcannula portion 616, and may be better approximated by a different helix634 a with a relatively high pitch (e.g., 120 mm) at the distal end 626.The distal tip 626 may deviate from the pitch of the helix 634 whichapproximates the shape of the distal cannula portion 616. The distal tip626 of the cannula 612 may angle in toward a center axis 607 of thehelix.

The helix 634 may have a pitch such that the cannula 612 may be insertedinto position in the right heart using a screw motion. The screw motionpositions the cannula 612, and in particular the distal tip 626 of thecannula 612, during insertion such that the distal tip 626 of thecannula 612 passes through the tricuspid valve, the right ventricle andpulmonary valve and into the pulmonary artery. The cannula 612 bodyfollows the distal tip 626 through the anatomy of the heart along thehelical pathway. The cannula 612 is positioned in the right heartwithout need for extensive repositioning.

FIG. 8 shows a catheter 800 with a helical shape positioned in the rightheart 801 of a patient according to certain implementations. Thecatheter 800 includes a catheter body 803, a pump assembly 808, acannula 812, and a control unit 850. The catheter body 803 includes acatheter proximal end 804 and a catheter distal end 802. The controlunit 850 is coupled to the catheter body 803 at the catheter proximalend 804. The pump assembly 808 is coupled to the catheter body 803 atthe catheter distal end 802. The pump assembly 808 may include a housing813 for a rotor. The cannula 812 is coupled to the pump assembly 808 atthe distal end of the pump assembly 810. The cannula 812 comprises aproximal cannula portion 814 which is approximately straight along alongitudinal axis 806 of the catheter body 803. The cannula 812 furthercomprises a distal cannula portion 816 which approximates a helicalshape fit to the interior anatomy of the right heart 801. The helicalshape of the distal cannula portion 816 may have a curvature based onthe anatomic path that the cannula 812 is designed to traverse. Thecannula 812 includes inlet ports 822 located on the proximal cannulaportion 814, and outlet ports 820 located at a distal tip 826 of thecannula 812. The distal tip 826 of the cannula 812 may be angled towarda toward a center axis of the helix 807 approximating the curvature ofthe distal cannula portion 816. The cannula 812 includes a flexibleprojection 824 coupled to the cannula 812 at the distal end of thecannula portion 818. The flexible projection 824 mechanically extendsthe cannula 812 such that the cannula 812 does not traumatically impactthe interior walls of the heart after insertion and positioning. As willbe appreciated, the catheter 800 need not include this flexibleprojection 824.

The cannula 812 may be percutaneously inserted or surgically implantedin the right heart of a patient. The cannula 812 can be placed in theright heart of a patient by insertion through a femoral artery and/orover a guidewire. The cannula 812 is inserted into the right heart 801through the inferior vena cava 836 and right atrium 838, through thetricuspid valve 840 into the right ventricle 842 and finally through thepulmonary valve 844 and into the pulmonary artery 846. The cannula 812can be advanced through the heart using a simple screw-like motion torotate and translate the helically-shaped cannula 812 as described inFIG. 3. When in position, the cannula 812 traverses from the inferiorvena cava 836 to the pulmonary artery 846. In some implementations, thecannula 812 extends into the pulmonary artery a distance of about 1 mm,2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm,60 mm or any other suitable distance beyond the pulmonary valve. When inposition in the right heart 801, the inlet ports 822 of the cannula 812are located in the inferior vena cava 836 and the outlet ports 820 ofthe cannula 812 are located in the pulmonary artery 846. In someimplementations, the outlet ports 820 of the cannula 812 are orientedsuch that the outflow is pointed in a downwards direction to facilitatethe delivery of blood into the pulmonary artery 846 during operation.

During use, the rotor enclosed in the housing 813 of the pump assembly808 creates a blood flow into the inlet ports 822 in the inferior venacava 836. The blood flow traverses the interior of the cannula 812 andexits the cannula 812 at the outlet ports 820 at the distal tip 826 ofthe cannula. The blood exits the cannula 812 into the pulmonary artery846, thus facilitating the blood flow from the inferior vena cava 836and right atrium 838 into the pulmonary artery 846.

The rotor in the pump assembly 808 provides the flow of blood throughthe cannula 812. As previously mentioned, in some implementations, therotor is driven by an implantable or external drive unit. In someimplementations, the drive unit is located in an external unit such asthe control unit 850. The pump assembly 808 may include a drive shaft(not shown) which is connected to the control unit 850. The control unit850 may include controls 856, 854 for the operation of the pump assembly808. For example, the control unit 850 may include a control 856 for theflow rate of the blood through the cannula 812. The flow rate of theblood through the cannula 812 can be controlled at the control unit 850by adjusting the rate of rotation of a rotor. The pump assembly 808 alsomay include a purge system to prevent the ingress of blood into the pumpassembly 808 and/or to cool and lubricate components of the pumpassembly 808. The catheter body 803 may include a fluid supply line 848to connect a purge system at the pump assembly 808 to a fluid supplyreservoir 852 located in the external control unit 850. The purge systemincluding the fluid supply reservoir 852 and fluid supply line 848 mayprovide purge fluid, lubricant, coolant, medicine, or any suitablehemocompatible fluid to the pump assembly 808. The control unit 850 mayfurther include indications and/or warnings to an operator regardingoperating conditions. In some implementations, the fluid supplyreservoir 852 and fluid supply controls 854 are located in a separatecontrol unit than the controls 856 for the catheter pump, rotor, andmotor.

The cannula designs disclosed herein are designed with a shape derivedfrom analysis of a representative sample of the patient population. Theregions of overlap in a representative sample population may be used todetermine the shape of the cannula. The shape of the cannula may bederived from the region of overlap between a significant proportion(86-96%) of the patient population. Further adaptations to the cannuladesign may be made based upon CT scans of a patient. In particular, if aCT scan of a patient shows that the right heart of the patient isanomalous, such as larger, smaller or differently shaped than a majorityof the population, the helical shape of the cannula may be altered orthe helix approximating the cannula may be chosen so as to fit the rightheart anatomy of the patient determined from the CT scan.

FIG. 9 shows an illustrative process 900 for placing a cannula in apatient's rightheart. In step 902, the catheter (e.g., catheter 100 ofFIG. 1, catheter 200 of FIG. 2A, or any other suitable catheter) isadvanced through the femoral vein and through the patient's vasculatureto the inferior vena cava. In some implementations, the catheter isintroduced using an introducer sheath and/or a guidewire. In someimplementations, the placement of the catheter is monitored byfluoroscopy or with the use of sensors incorporated into the catheter.The catheter may be configured for short-term use, such as during anemergency procedure or in conjunction with an imaging procedure. In someimplementations, the catheter is configured for long-term use as a fullyimplantable heart pump. The catheter may be used for long-termimplantation in a patient (e.g., >1 hr, >3 hr, >6 hr, >12 hr, >24 hr, >2days, >10 days, >20 days, >45 days, >60 days or any suitable duration).

Once the catheter has been advanced to the inferior vena cava, in step904, the distal tip of the catheter is rotated and translated throughthe tricuspid valve toward the pulmonary artery in a screw-like motion.The catheter includes a cannula (e.g., cannula 112 in FIG. 1, cannula212 in FIG. 2A, or any other suitable cannula), a portion of which isapproximated by a helix. The helix approximating the cannula shape ismatched to an average anatomy of the right heart including the tricuspidvalve, right ventricle and pulmonary valve. The rotation of the cannulain the direction of the helix advances the distal tip of the cannulathrough the tricuspid valve and into the right ventricle, with the bodyof the cannula following along the path of the helix. The distal tip ofthe cannula may deviate from the helical path in order to facilitate thesuccessful advancement of the cannula through the tricuspid valve towardthe pulmonary artery. Once in the right ventricle, the screw-likerotation of the helical cannula leads to the positioning of the cannulawith the distal tip pointing toward the pulmonary valve. In someimplementations, a flexible projection (e.g., flexible projection 224 inFIG. 2A, flexible projection 524 in FIG. 5, or any other suitableflexible projection) is attached at the distal tip of the cannula. Theflexible projection can mechanically extend the cannula and preventstraumatic contact between the cannula and the interior walls of theheart.

The distal tip of the cannula is advanced through the pulmonary valveand into the pulmonary artery in step 906. The cannula is thuspositioned such that the cannula traverses the tricuspid valve, rightventricle, pulmonary valve and pulmonary artery. The inlet ports arepositioned in the inferior vena cava, while the outflow ports arepositioned above the pulmonary valve in the pulmonary artery. Thecannula can then be used to provide an additional blood flow from theinferior vena cava to the pulmonary artery. In some implementations, aflow rate of 4 fpm or more is provided through the cannula within theright heart of a patient. In some implementations, a flow rate of 3 lpm,3.5 lpm, 4 lpm, 4.5 lpm 5 lpm, 6 lpm or any other suitable flow rate isprovided. In some implementations, the flow rate is chosen based on theneeds of the patient.

The helically-shaped cannula mimics the interior anatomy of the rightheart to facilitate advancement of the cannula into the heart and properpositioning to provide cardiac support in the right heart. The cannulacan be positioned to span from the inferior vena cava, through thetricuspid valve, through the right ventricle and through the pulmonaryvalve to extend into the pulmonary artery. Blood may flow through thecannula from the inferior vena cava to the pulmonary artery where itexits the outlet ports of the cannula to join the blood flow in thepulmonary artery. The shape of the cannula facilitates the insertionprocess for health care professionals. The helical shape of the cannulareflects the average anatomy of a sample patient population such thatthe probability of proper placement and fit of the cannula within theright heart of a patient is improved. The cannula may further becomposed of a stable material, since the shape allows the insertion ofthe cannula without the need for a flexible or bendable cannula.Cannulas with an increased stability enable the use of implantable orlong-term use cannulas.

The foregoing is merely illustrative of the principles of thedisclosure, and the apparatuses can be practiced by other than thedescribed embodiments, which are presented for purposes of illustrationand not of limitation.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

1-19. (canceled)
 20. A heart pump assembly comprising: a rotor; ahousing sized for percutaneous insertion and enclosing the rotor, thehousing having a distal end portion; a cannula coupled to the distal endportion of the housing, the cannula comprising a proximal cannulaportion and a distal cannula portion, the distal cannula portion havingan approximately helical shape.
 21. The heart pump assembly of claim 20,wherein the helical shape approximated by the distal cannula portion hasan axis parallel to a longitudinal axis of the proximal cannula portion.22. The heart pump assembly of claim 21, wherein the helical shapeapproximated by the distal cannula portion has a diameter between about20 mm and 40 mm.
 23. The heart pump assembly of claim 22, wherein thehelical shape approximated by the distal cannula portion has a pitchbetween about 70 mm and 120 mm.
 24. The heart pump assembly of claim 23,wherein a distal tip of the cannula is angled toward a center of thehelical shape axis.
 25. A method of placing a catheter in a patient'sright heart, the method comprising: advancing the catheter through thefemoral vein to the inferior vena cava, the catheter comprising a heartpump and a helically-shaped distal tip; simultaneously rotating andtranslating the helically-shaped distal tip through a tricuspid valvetoward the pulmonary artery in a screw-like motion; advancing thehelically-shaped distal tip through the pulmonary valve into thepulmonary artery.
 26. The method of claim 25, further comprisingpositioning the catheter across the pulmonary valve such that an outletport is positioned in the pulmonary artery.
 27. The method of claim 26,further comprising positioning the catheter such that an inlet port ispositioned in the inferior vena cava.
 28. The method of claim 27,wherein advancing the catheter through the femoral vein comprisesadvancing the catheter over a guidewire.